Morfološke značilnosti in porazdelitev vrtač v Sloveniji, študija vrtač na osnovi lidarskih podatkov

Dolines are small to intermediate enclosed depressions and are the most numerous karst feature in Slovenia. They are circular in plan form and vary in diameter from a few metres to over a kilometre. They are developed in limestone, dolomite, carbonate breccia and conglomerate and occupy different geomorphic settings. They were formed by various processes like dissolution, collapse, suffosion and transformation of caves to surface features by denudation. Publicly accessible lidar data, provided by a nationwide laser scanning project of Slovenia, was used for this study. To catalogue the dolines, we manually label a fraction of the digital elevation model (DEM) with a binary mask indicating if the area is a doline or not. We then train a slightly modified u-net, a type of machine learning algorithm, on the labelled territory. Using the trained algorithm, we infer the binary mask on the entire DEM. We convert the resulting mask into an ESRI Shapefile and manually verify the results. We note that the training and inference are error prone on types of relief that were less common in the training set (e.g., the relatively uncommon collapse dolines). We believe manual verification mitigates most of these errors, so the resulting map is a good basis for the doline study. We have made our georeferenced catalogue of dolines available at https://dolines.org/ (Mihevc & Mihevc 2021). Dolines are found in most of the karst areas, except mountains where they were eroded by glacial action or covered by glacial deposits. We detected 471,192 dolines and divided them into three genetic types. Most abundant are solution dolines (470,325). The average doline is 9 m deep, has a diameter of 42 m and a volume of 14,098 m3. The density of dolines on levelled surfaces can be as high as 500/ per km2. They are absent from the floors of poljes and steeper slopes, and are less abundant on sloping surfaces. We have identified 314 dolines to be of collapse origin. The mean depth of collapse dolines is 49 m, and 20 of them are deeper than 100 m. The mean volume is 1.2 million m3, with the largest having a volume of 11.6 million m3. Most of the collapse dolines can be found close to ponors or springs or corridors where large underground rivers flow. We have detected 553 suffosion dolines formed by suffosion of sediments in blind valleys or on poljes. This basic data set for dolines enables further study and comparison of dolines with the geology and topography of the karst.Vrtače so majhne do srednje velike zaprte depresije in so najštevilčnejša kraška oblika v Sloveniji. So krožne oblike in imajo premer od nekaj metrov do več kot kilometer. Nastanejo na apnencu, dolomitu, karbonatni breči in konglomeratu. Nastanejo v različnih geomorfnih okoljih, in to z različnimi procesi, kot so raztapljanje, grezanje, sufozija in pretvorba jam v površinske oblike z denudacijo. Za to študijo so bili uporabljeni javno dostopni lidarski podatki, ki so bili zajeti s skeniranjem celotnega ozemlja Slovenije. Za katalogiziranje vrtač del digitalnega modela višin ročno označimo z binarno masko, ki označuje, ali je območje vrtača ali ne. Nato na označenem ozemlju učimo algoritem globokega strojnega učenja u-net. Z algoritmom napovemo binarno masko na celotnem ozemlju Slovenije. Nastalo masko pretvorimo v format SRI Shapefile in ročno preverimo rezultate. Pri delu smo ugotovili, da so napake strojnega učenja in napovedovanja binarne maske večja pri tistih vrstah vrtač, ki so bile manj pogoste v učnih podatkih (npr. pri razmeroma redkih udornih vrtačah). Menimo, da smo z ročnim preverjanjem odpravili večino napak, zato je dobljeni katalog vrtač dobro izhodišče za nadaljnjo študijo. Georeferencirani katalog vrtač je dostopen na spletnem naslovu https://dolines.org/. Vrtače zasedajo večino kraških območij, razen planot, kjer so bile zaradi ledeniškega delovanja erodirane ali prekrite z ledeniškimi nanosi. Odkrili smo 471.192 vrtač in jih razvrstili v tri tipe glede na njihov izvor. Najpogostejše so korozijske vrtače (470.325 primerkov). Povprečna vrtača je globoka 9 m, ima premer 42 m in prostornino 14.098 m3. Gostota vrtač na uravnanih površinah je lahko tudi do 500/ vrtač na km2. Vrtač ni na dnu polj in na strmih pobočjih, manj jih je na nagnjenih površinah. Določili smo 314 udornih vrtač. Povprečna globina udornih vrtač je 49 m, 20 pa jih je globljih od 100 m. Povprečna prostornina je 1,2 milijona m3, največja pa ima prostornino 11,6 milijona m3. Večina udornih vrtač je blizu ponorov, izvirov ali tokov velikih podzemnih rek. Odkrili smo še 553 sufozijskih vrtač, ki so nastale s spiranjem sedimentov v slepih dolinah ali na poljih. Narejeni katalog vrtač omogoča nadaljnje proučevanje in primerjavo vrtač z geologijo in topografijo krasa

Led v jamah in njegov vpliv na toplotni obrat ter permafrost na primeru Velike ledene jame v Paradani, Smrekove drage in sosednjih vrtač

In the Velika ledena jama v Paradani, in the karstic blowholes on the slopes of Smrekova draga and in the nearby dolines I measured and interpreted air temperatures and the effect of the summer outflow of cold air from them into the surrounding area. In winter, cold air enters the cave, radically cooling the entrance part of the cave, where for this reason there is permanent cave ice. The summertime circulation is reversed: emerging from the inner part of cave, which has an average temperature of around 4° C, is air which only when it transits through the sub-cooled entrance part is then cooled to around 1° C. This air comes to the surface and in the hollow at the cave entrance maintains a distinct thermal inversion during the warm part of the year. There is a similar air circulation and similar development of annual temperatures observed at the vents, where cave air emerges through rubble spread over cave entrances on slopes or at the bottom of dolines. The stable summer air temperatures of around 1° C in the vents where I conducted measurements indicate that underneath them there is also permafrost or sub-cooled rock and permanent ice. This is created and preserved, just like in the caves, due to the advection of cold air in winter. In Trnovski gozd, such karstic permafrost is found at an altitude of 1,100 m above sea level. The outflow of cold air from the vents in the summer, just like inside the cave, causes a distinct thermal inversion in dolines on the surface.V Veliki ledeni jami v Paradani, v dihalnikih na pobočjih Smrekove drage in v bližnjih vrtačah sem meril in interpretiral temperature zraka ter vpliv poletnega iztekanja hladnega zraka iz njih v okolico. V jamo pozimi vstopa mrzel zrak, ki močno podhladi vhodni del jame, kjer se zato ohranja stalni jamski led. Poletna cirkulacija je obrnjena; iz notranjega dela jame, ki ima povprečno temperaturo okrog 4° C piha zrak, ki se šele ob prehodu skozi podhlajeni vhodni del jame ohladi na okrog 1° C. Ta zrak izhaja na površje in v kotanji pri vhodu v jamo vzdržuje v topli polovici leta izrazit toplotni obrat. Podobno zračno cirkulacijo in podoben potek letne temperature imajo tudi dihalniki, kjer jamski zrak izhaja skozi grušč, ki je zasul jamske vhode na pobočjih ali v dnu vrtač. Stabilne poletne temperature zraka okrog 1° C v dihalnikih, v katerih sem opravil meritve kažejo, da tudi pod njimi obstaja permafrost oziroma podhlajena kamnina in stalni led. Ta nastane in se ohranja, enako kot v jamah, zaradi advekcije mrzlega zraka pozimi. Na Trnovskem gozdu je tak kraški permafrost v nadmorski višini okrog 1100 m. Iztekanje hladnega zraka iz dihalnikov povzroča poleti prav tako kot pri jami, izrazit toplotni obrat v kotanjah in na površju

The Age of Karst Relief in West Slovenia

The age of a karst can be defined as the time when the karst rocks were uplifted out of the sea. The other view of the age of karst is to define the age of certain karst features or assemblages of karst features. On the Kras plateau there is a variety of forms that were formed at quite different times, but due to karst evolution, they coexist in today’s relief. On the plateau, that is slowly rising, the hydrological zones in karst surface are moving downwards. Streams from the side ceased to flow on the karst and former leveled surface that was formed in conditions of high ground water is dissected by numerous dolines. Blind valleys are incised at the side and some of them show the influence of recent tectonics. The lowering of relief by corrosion exposes caves that have formed deep beneath the surface and creates unroofed caves that become a part of the surface topography. From the morphological comparison of the unroofed caves, blind valleys and levelled surfaces and by dating of the sediment and considering the age of tectonic phases we can reconstruct the evolution and estimate the age of the karst landscape

Investigation of Structure of Various Surface Karst Formations in Limestone and Dolomite Bedrock with Application of the Electrical Resistivity Imaging

Karst landforms are developed in different kind of rocks and in different structural settings. Authors are presenting some results of profile measurement of Electrical resistivity imaging in some dolines and collapse dolines that developed in lime­stone and dolomite in Slovenia. Selected features are examples of surface karst landforms whichcould be morphologically de­fined as typical of its kind. For electrical resistivity imaging data collection was used SuperSting R1/IP earthresistivity meter. Electrical resistivity imaging method was applied for researchof material characteristics beneathsurface of karst landforms. Materials withhigher portion of water as fractured bedrock or clay are less resistant to electrical current than unfractured bed­rock. Application of the ERI method has turned out as appro­priate for detailed investigation of surface karst landforms

Analiza regulacije trga mobilnih komunikacij iz vidika korelacij med storitvami

The aim of this article is to answer the question if regulation of call termination in mobile market is sufficient for effective regulation and to ensure the effective competition. The article will analyse the possibility to follow European Commission recommendations without additional market analyses. EC recommends analysing only the market for call termination on each individual mobile network to ensure the efficient competition on the whole mobile market. EC defines, based on demand and supply substitution and obstacles to enter the market, new 7 electronic communications markets and only one on the mobile market. National Regulatory Authorities mostly just follow the recommendation. The article defines which additional elements need to be taken into consideration and when to ensure the effective competition, based on co-relation between the services of termination and origination and its mathematical co-relation to market share. The article defines the border between the regulation, which can only follow EC recommendation and regulation of additional market definitions. Analysis and findings of the article show that because of correlations on the market is impossible to ensure an effective competition, just with the definition of mobile market for call termination on individual network on each geographical market.Namen članka je odgovoriti na vprašanje ali je le regulacije zaključevanja klicev na trgu mobilnih komunikacij dovolj za rešitev konkurenčnega problema na vsakem geografskem trgu ter posledično zagotavlja popolno konkurenco na trgu. Evropska komisija je v svojih najnovejših priporočil priporočila definiranje in analizo le trga zaključevanja klicev v posamično mobilno omrežje. Članek bo na podlagi matematičnih korelacij med zaključevanjem in posredovanjem klicev ter korelacij glede na tržni delež podal katere elemente je potrebno dodatno analizirati in upoštevati pri regulaciji trga mobilnih komunikacij. Članek bo definiral meje pri katerih je potrebno izvesti dodatne analize ter definiranje dodatnega trga, ki ga ni v trenutno veljavnih priporočilih Evropske komisije. Analize in ugotovitve v tem članku dokazujejo, da samo analiza priporočenih trgov s strani Evropske komisije ne zadostujejo za učinkovito regulacijo trga mobilnih komunikacij

Predicting of Roll Surface Re-Machining Using Artificial Neural Network

The paper presents a model for predicting the roll wear in the hot rolling process. It includes all indicators from the entire continuous rolling line that best predict the roll wear in the hot rolling process. Data for model development were obtained from annual production on the first rolling stand of the continuous roll mill. The main goal of the research was to determine significant parameters that affect the wear of the roll in the process of hot rolling. It has been found that the amount of rolled material before the re-machining of the roll surface has the greatest impact on the life of the roll contour. Therefore, the amount of material rolled before re-machining of the roll was used to estimate the wear of the roll. An artificial neural network was used to predict this amount of rolled material and was validated using data from one-year production

Concentration and stable carbon isotopic composition of CO2 in cave air of Postojnska jama, Slovenia

Partial pressure of CO2 (pCO2) and its isotopic composition (δ13CairCO2) were measured in Postojnska jama, Slovenia, at 10 locations inside the cave and outside the cave during a one-year period. At all interior locations the pCO2 was higher and δ13CairCO2 lower than in the outside atmosphere. Strong seasonal fluctuations in both parameters were observed at locations deeper in the cave, which are isolated from the cave air circulation. By using a binary mixing model of two sources of CO2, one of them being the atmospheric CO2, we show that the excess of CO2 in the cave air has a δ13C value of -23.3 ± 0.7 ‰, in reasonable agreement with the previously measured soil-CO2 δ13C values. The stable isotope data suggest that soil CO2 is brought to the cave by drip water

Dating of the Udin Boršt conglomerate terrace and implication for tectonic uplift in the northern part of the Ljubljana Basin (Slovenia)

EN:The northwestern part of the Ljubljana Basin is filled mostly with fluvioglacial sediments deposited by rivers coming from Alpine mountain groups. The Tržiška Bistrica River, flowing from the Karavanke Mountains, has deposited a large alluvial fan consisting predominantly of carbonate pebbles with subordinate amounts of siliciclastic pebbles. The oldest infill, cemented into a conglomerate terrace named Udin Boršt, overlies an erosional surface on Oligocene mudstone. The thickness of the conglomerate terrace is up to 50 m. The conglomerate terrace is well karstified; the surface is dissected by numerous dolines and covered with a thick soil sequence. There are several caves. The most important are spring caves formed on the contact with the underlying impermeable basement. Samples of quartz pebbles were taken from the walls and ceiling in the 815 m long spring Arneševa Luknja Cave for cosmogenic nuclides burial age dating. The calculated burial age yielded an age of 1.86 ± 0.19 Ma that gives (i) the age of the oldest known infill in the Ljubljana Basin and (ii) indicates the time of change of the sedimentary system in the Basin from erosion to deposition. The age of the Udin Boršt karst and caves is significantly younger. The age dates provide grounds for a first relatively firm estimate of the long-term tectonic uplift of the Udin Boršt terrace to be between 0.06 and 0.04 mm/yr. This tectonic uplift rate may be related to the activity of the regional Sava Fault.SLO:Severozahodni del Ljubljanske kotline pokrivajo večinoma fluvioglacialni sedimenti, ki so jih odložile reke iz alpskih gorskih skupin. Tržiška Bistrica, ki priteka iz Karavank je odložila velik vršaj. V njem prevladujejo karbonatni prodniki z manjšim deležem siliciklastičnih prodnikov. Ta najstarejša zapolnitev, sprijeta v konglomeratno teraso Udin boršt, leži na erozijskem površju oblikovanem v oligocenskih glinovcih. Debelina konglomeratne terase je do 50 m. Konglomeratna terasa je dobro zakrasela, površje pa je razčlenjeno z vrtačami in pokrito z debelo plastjo prsti. V njej je več jam, med katerimi so najpomembnejše izvirne jame, ki so se oblikovale na stiku z neprepustno podlago. V 815 m dolgi Arneševi luknji smo vzeli iz sten in stropa jame vzorec iz kremenovih prodnikov za določitev pokopne starosti prodnega zasipa s kozmičnimi nuklidi. Izračunana starost prekritja sedimentov je 1.86 ± 0.19 Ma. Ta datacija določa (i) starost najstarejše sedimentne zapolnitve v Ljubljanski kotlini in (ii) čas spremembe v sedimentacijskem sistemu kotline iz erozije v sedimentacijo. Starost kraških oblik in jam v Udin borštu je znatno mlajša. Starost sedimenta daje tudi osnovo za relativno trdno določitev tektonskega dviga terase Udin boršta na 0,06 do 0,04 mm/yr. Ta tektonski dvig je verjetno povezan z premiki ob regionalnem savskem prelomu

High-Reesolution Magnetostratigraphy of Speleothems from Snežna jama, Kamnik-Savinja Alps, Slovenia

Snežna jama je velika vodoravna fosilna epifreatična jama. Leži v grebenu Raduhe, V delu Kamniško Savinjskih Alp v SV Sloveniji. V bližini vhoda je v jami v okrog 3 m visok prerezu razgaljeno zaporedje plasti sig s številnimi prekinitvami rasti in izdatno terigeno komponento v spodnjem delu. V 2,4 m dolgem zveznem profilu smo vzeli zaporedne vzorce , ki smo jih proučili z termalno demagnetizacijsko metodo in metodo spreminjajočega magnetnega polja. Magnetostratigrafske analize so pokazale 7 normalnih in 6 reverznih magnetocon. Magnetne lastnosti se dobro ujemajo z litološko mejo v profilu sige. Spodnji del profila kaže večjo magnetno susceptibilnost in močnejšo remanentno magnetizacijo. Sprememba lastnosti v profilu nakazuje pomembno paleogeografsko spremembo v času nastajanja sige. Starost sige sega izven dosega datacijske metode alfa spektrometrične analize U razpadne vrste; ravnotežje U izotopov pa nakazuje starost večjo od 1,2 Ma. Najbolj verjetna starost sige, ki jo dobimo z korelacijo s primerjavo z geomagnetno časovno skalo je bodisi 3,0 do 5,0 ali 1.8 do 3.6 Ma. Starost jame lahko primerjamo z nekaterimi brezstropimi jamami na krasu v JZ Sloveniji, kjer sedimentacijo v jamah postavljamo v mesinsko obdobje. Snežna jama je bila dvignjena v sedanjo višino z mlajšimi (plio-pleistocenskimi) dvigovanji Alpskega loka.The Snežna jama Cave is located in the Kamnik-Savinja Alps, NE Slovenia, in a Raduha Ridge. The cave is a huge, more or less horizontal fossil phreatic/epiphreatic conduit. It is penetrated by vertical shafts – invasion vadose (proglacial) caves. Close to the cave entrance, there is about 3 m high wall composed of speleothems - a complex sequence of flowstone with numerous breaks in deposition, six of them are principal. The lower part of the profile (about 85 cm) contains abundant terrigenous component (terra rossa-derived clay). Stalagmites developed in several periods are completely buried by nearly horizontal younger sequences of flowstone. Continuous speleothem log was recovered from the profile in a total length of about 2.4 m. The rock column was cut to cubes in the laboratory (2x2x2 cm) and studied both by thermal demagnetisation (23 samples, 12 steps - 20 to 620 ¡C) and alternating field method (98 samples, 14 steps - 1 to 100 mT). Magnetic properties identified the lithological boundary. In contrast to the upper part, the lower one shows both higher magnetic susceptibility and higher remanent magnetisation. The turn point can indicate important palaeogeographical change. Magnetostratigraphic log is composed of 7 normal and 6 reverse polarised magnetozones. The age of speleothems detected by the U-series alpha-counting spectrometry falls outside the method range, i.e. over 350 ka. Uranium isotopic equilibria indicate the age over 1.2 Ma. The age of the fill is pre-Quaternary, clearly older than 1.77 Ma. The most probable age from correlation with geomagnetic polarity timescales is about 3.0 to 5.0 or 1.8 to 3.6 Ma. Both possibilities can indicate the growth rate of speleothems of about 1.1 to 1.3 m per 1 Ma. The age of speleogenesis can be compared to some of unroofed caves in the area of the Classical Karst (SW Slovenia) connected with the Messinian period. Snežna jama was uplifted to high altitudes by younger (Plio-Pleistocene) uplift of the Alpine chain

Palaeomagnetic research on karst sediments in Slovenia

We have conducted palaeomagnetic and magnetostratigraphic research on karst sediments in Slovenia since 1997. More than 2,000 samples were taken and analysed in 36 different profiles at 21 locations in caves and on the surface. Standard palaeomagnetic analyses were used (thermal and alternating field demagnetisation, magnetic susceptibility measurements, etc.). There is no evidence of younger marine deposition than Eocene in the SW part of Slovenia. Younger sediments occur only in caves and very rarely on the karst surface (different soils and a few remains of terrigeneous sediments). Marine and terrestrial Tertiary to Plio–Quaternary deposition occurs in the SE and E Slovenia. Chronostratigraphy of cave sediments in SW Slovenia completed by Rado Gospodarič in the 1980s was based on Pleistocene warm/cold cycles. Later Th/U dating indicated that speleothems from different caves in Slovenia are older. New dating principally results from palaeomagnetism and magnetostratigraphy of cave sediments calibrated, in some sites, by Th/U, palaentological and geomorphological analyses. Calibrated data contributed to the reconstruction of speleogenesis, deposition in caves, and indirectly to the evolution of karst surfaces and succession of tectonic movements. The evolution of caves in the Slovenian territory took part within one post-Eocene karstification period. This period continues to the present, and can be subdivided into individual, but not well limited, phases related to Cenozoic palaeogeographical changes. The period contains distinct phases of massive deposition in caves with as yet still preserved sediments dated to about 5.4–4.1 Ma (Miocene–Pliocene), 3.6–1.8 Ma (Pliocene) and Quaternary, following the cessation of Miocene deposition in the Pannonian Basin in the central, E and SE Slovenia and post-Messinian evolution in the SW and W Slovenia